Modernize packaging-related things in Red (#5924)

tox.ini

@@ -10,13 +10,14 @@ envlist =
     docs
     style
 skip_missing_interpreters = True
+isolated_build = True
 
 [testenv]
 description = Run tests and basic automatic issue checking.
 whitelist_externals =
     pytest
     pylint
-extras = voice, test
+extras = test
 setenv =
     TOX_RED = 1
 commands =
@@ -28,7 +29,7 @@ commands =
 description = Run pytest with PostgreSQL backend
 whitelist_externals =
     pytest
-extras = voice, test, postgres
+extras = test, postgres
 setenv =
     TOX_RED = 1
     RED_STORAGE_TYPE=postgres
@@ -53,7 +54,7 @@ setenv =
     # Prioritise make.bat over any make.exe which might be on PATH
     PATHEXT=.BAT;.EXE
 basepython = python3.8
-extras = docs
+extras = doc
 commands =
     sphinx-build -d "{toxworkdir}/docs_doctree" docs "{toxworkdir}/docs_out/html" -W --keep-going -bhtml
     sphinx-build -d "{toxworkdir}/docs_doctree" docs "{toxworkdir}/docs_out/doctest" -W --keep-going -bdoctest